#include <stdio.h>
#include <stdlib.h>

int main()
{
    int dayTh;
    float Udis, currentHeight, firstClaim, HeightOfWell, downDis, fagtigue;
    while (scanf("%f %f %f %f", &HeightOfWell, &Udis, &downDis, &fagtigue) != EOF)
    {
        if (HeightOfWell == 0)
            break;
        currentHeight = 0;
        firstClaim = Udis;
        dayTh = 0;
        while (1)
        {
            currentHeight += Udis;
            Udis -= fagtigue / 100 * firstClaim;
            if (Udis < 0)
                Udis = 0;
            dayTh++;
            if (currentHeight > HeightOfWell)
            {
                printf("success on day %d\n", dayTh);
                break;
            }
            else
            {
                currentHeight -= downDis;
                if (currentHeight < 0)
                {
                    printf("failure on day %d\n", dayTh);
                    break;
                }
            }
        }
    }
    return 0;
}